Clinical Outcomes and Safety of Meropenem-Colistin versus Meropenem-Tigecycline in Patients with Carbapenem-Resistant Acinetobacter baumannii Pneumonia

Treatment of infections caused by carbapenem-resistant Acinetobacter baumannii

Patients with severe carbapenem-resistant Acinetobacter baumannii (CRAB) infections currently face significant treatment challenges. When patients display signs of infection and the clinical suspicion of CRAB infections is high, appropriate treatment should be immediately provided. However, current treatment plans and clinical data for CRAB are limited. Inherent and acquired resistance mechanisms, as well as host factors, significantly restrict options for empirical medication. Moreover, inappropriate drug coverage can have detrimental effects on patients. Most existing studies have limitations, such as a restricted sample size, and are predominantly observational or non-randomized, which report significant variability in patient infection severity and comorbidities. Therefore, a gold-standard therapy remains lacking. Current and future treatment options of infections due to CRAB were described in this review. The dose and considerable side effects restrict treatment options for polymyxins, and high doses of ampicillin-sulbactam or tigecycline appear to be the best option at the time of initial treatment. Moreover, new drugs such as durlobactam and cefiderocol have substantial therapeutic capabilities and may be effective salvage treatments. Bacteriophages and antimicrobial peptides may serve as alternative treatment options in the near future. The advantages of a combination antimicrobial regimen appear to predominate those of a single regimen. Despite its significant nephrotoxicity, colistin is considered a primary treatment and is often used in combination with antimicrobials, such as tigecycline, ampicillin-sulbactam, meropenem, or fosfomycin. The Infectious Diseases Society of America (IDSA) has deemed high-dose ampicillin-sulbactam, which is typically combined with high-dose tigecycline, polymyxin, and other antibacterial agents, the best option for treating serious CRAB infections. A rational combination of drug use and the exploration of new therapeutic drugs can alleviate or prevent the effects of CRAB infections, shorten hospital stays, and reduce patient mortality.

Clinical efficacy and safety of tigecycline based on therapeutic drug monitoring for carbapenem-resistant Gram-negative bacterium pneumonia in intensive care units

BACKGROUND

We investigated the associations between the different doses of tigecycline, its efficacy and safety, and the role of tigecycline therapeutic drug monitoring for patients in the intensive care unit.

METHODS

This study was a single-center cohort including patients infected with multidrug-resistant Acinetobacter baumannii (MDR-AB) and multidrug-resistant Klebsiella pneumoniae (MDR-KP) causing pulmonary infections. The steady-state plasma concentration after tigecycline administration was determined by High-Performance Liquid Chromatography (HPLC) in patients admitted to the ICU between October 2020 and December 2021. Multivariate analyses of tigecycline's clinical efficacy and safety were performed to control confounding factors.

RESULTS

For this study, we included 45 patients and 45 blood samples to determine steady-state trough concentrations of tigecycline. All patients were divided into the High Dose (HD) and Standard Dose (SD) groups. The median trough concentration of tigecycline was 0.56 μg/mL in the HD group, which was higher than in the SD group (0,21 μg/mL), p = 0.000. There was no significant difference between the two groups of patients in terms of bacterial eradication rate, mortality rate, and clinical efficacy. Multiple regression analysis showed that the ICU days were correlated with mortality OR 1.030(1.005-1.056), p = 0.017. APACHE II was significantly associated with clinical efficacy OR 0.870(0.755-1.002), p = 0.045. The level of fibrinogen decline in the HD group was significantly higher than in the SD group (-3.05 ± 1.67 vs -1.75 ± 1.90), p = 0.038. We identified that age and tigecycline treatment duration influenced fibrinogen decline.

CONCLUSIONS

Tigecycline plasma concentrations are significantly increased when using a high dose. However, the plasma concentration of tigecycline is not correlated with clinical efficacy and adverse reactions. Fibrinogen decline appears to be related to the patient's age and days of tigecycline. Large sample data are still needed to confirm the clinical guidance significance of tigecycline TDM.

Tigecycline-Containing Regimens and Multi Drug-Resistant Acinetobacter baumannii: A Systematic Review and Meta-Analysis

Introduction: The use of tigecycline (TG) for the treatment of Acinetobacter baumannii is controversial. In this systematic review and meta-analysis, we aimed to better explore the safety and efficacy of TG for the treatment of multi drug-resistant (MDR) Acinetobacter. Methods: We searched PubMed/MEDLINE, Scopus, Cochrane Central, and Web of Science to identify studies reporting the clinical and microbiological efficacy and safety of regimens containing TG in patients with drug susceptibility testing (DST)-confirmed MDR A. baumannii, published until December 30, 2022. Observational studies were included if they reported clinical and microbiological efficacy of TG-based regimens. The Newcastle-Ottawa Scale (NOS) and Joana Briggs Institute (JBI) critical appraisal tool were used to assess the quality of included studies. Results: There were 30 observational studies, of which 19 studies were cohort and 11 studies were single group studies. Pooled clinical response and failure rates in the TG-containing regimens group were 58.1 (95% confidence interval [CI] 49.2-66.6) and 40.2 (95% CI 31.1-50.0), respectively. The pooled microbiological response rate was 32.1 (95% CI 19.8-47.5), and the pooled all-cause mortality rate was 41.1 (95% CI 34.1-48.4). Pooled clinical response and failure rates in the colistin-based regimens group were 52.7 (42.7-62.5) and 43.1 (33.1-53.8), respectively. The pooled microbiological response rate was 42.9 (16.2-74.5), and the pooled all-cause mortality rate was 34.3 (26.1-43.5). Conclusions: According to our results, the efficacy of the TG-based regimen is the same as other antibiotics. However, our study showed a high mortality rate and a lower rate of microbiological eradication for TG compared with colistin-based regimen. Therefore, our study does not recommend it for the treatment of MDR A. baumannii. However, this was a prevalence meta-analysis of observational studies, and for better conclusion experimental studies are required.

Clinical effectiveness of tigecycline in combination therapy against nosocomial pneumonia caused by CR-GNB in intensive care units: a retrospective multi-centre observational study

BACKGROUND

Tigecycline has in vitro bacteriostatic activity against a broad spectrum of bacteria, including carbapenem-resistant Gram-negative bacteria (CR-GNB). However, the role of tigecycline in treatment of nosocomial pneumonia caused by CR-GNB remains controversial and clinical evidences are limited. We aimed to investigate the clinical benefits of tigecycline as part of the combination treatment of nosocomial CR-GNB pneumonia in intensive care unit (ICU).

METHODS

This multi-centre cohort study retrospectively enrolled ICU-admitted patients with nosocomial pneumonia caused by CR-GNB. Patients were categorized based on whether add-on tigecycline was used in combination with at least one anti-CR-GNB antibiotic. Clinical outcomes and all-cause mortality between patients with and without tigecycline were compared in the original and propensity score (PS)-matched cohorts. A subgroup analysis was also performed to explore the differences of clinical efficacies of add-on tigecycline treatment when combined with various anti-CR-GNB agents.

RESULTS

We analysed 395 patients with CR-GNB nosocomial pneumonia, of whom 148 received tigecycline and 247 did not. More than 80% of the enrolled patients were infected by CR-Acinetobacter baumannii (CRAB). A trend of lower all-cause mortality on day 28 was noted in tigecycline group in the original cohort (27.7% vs. 36.0%, p = 0.088). In PS-matched cohort (102 patient pairs), patients with tigecycline had significantly lower clinical failure (46.1% vs. 62.7%, p = 0.017) and mortality rates (28.4% vs. 52.9%, p < 0.001) on day 28. In multivariate analysis, tigecycline treatment was a protective factor against clinical failure (PS-matched cohort: aOR 0.52, 95% CI 0.28-0.95) and all-cause mortality (original cohort: aHR 0.69, 95% CI 0.47-0.99; PS-matched cohort: aHR 0.47, 95% CI 0.30-0.74) at 28 days. Kaplan-Meier survival analysis in subgroups of patients suggested significant clinical benefits of tigecycline when added to a colistin-included (log rank p value 0.005) and carbapenem-included (log rank p value 0.007) combination regimen.

CONCLUSIONS

In this retrospective observational study that included ICU-admitted patients with nosocomial pneumonia caused by tigecycline-susceptible CR-GNB, mostly CRAB, tigecycline as part of a combination treatment regimen was associated with lower clinical failure and all-cause mortality rates.